Primer Cup - A small metal cup, into which the primer mixture
Most primer cups are made of 70/30 cartridge brass. The metal of the
cup must be able to resist the pressure developed when the priming
mixture burns or primer leaks pierced primers and other irregularities
will result. At the same time, the thickness of the primer cup must
be kept within certain limits or the primer will be lacking in
It is in the interest of the manufacturers to prevent primer cups from
becoming too hard.
Primer cups are usually made of cartridge bass, although copper,
nickel-plated copper or brass, copper alloy and zinc-coated steel cups
are also encountered.
Most metallic primer cups are made of cartridge brass but steel may
also be used.
Primer cups are produced on a cupping press.
After cupping, the parts are tumbled to remove sharp edges at the
open end of the cups. This smooths the cup, making insertion in
cartridge cases easier. Most commercial primer cups are nickel-plated
for corrosion resistance.